QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

7 km W of Sheridan, Montana

· 10 km deep · released about 14 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 33 kmSilver Bow County 56 kmBeaverhead County 60 kmJefferson County 76 kmGallatin County 88 kmDeer Lodge County 96 kmBroadwater County 114 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
Magnitude
M 1.8 (ml)
Depth
10 km below the surface
Felt
no reports yet
Nearest
Madison County, 33 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2001 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 14 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 790,000× the energy of this one
  3. Around the size people start to feel M 3.0 70× the energy of this one
  4. This earthquake M 1.8 about 14 lb of TNT

Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

Where

Epicentre 45.4638, -112.2925. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Madison County, MT 33 km (21 mi) WNW of here earthquakes near Madison County
Silver Bow County, MT 56 km (35 mi) SSE of here earthquakes near Silver Bow County
Beaverhead County, MT 60 km (37 mi) NE of here earthquakes near Beaverhead County
Jefferson County, MT 76 km (47 mi) SSW of here earthquakes near Jefferson County
Gallatin County, MT 88 km (55 mi) W of here earthquakes near Gallatin County
Deer Lodge County, MT 96 km (60 mi) SE of here earthquakes near Deer Lodge County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

52 earthquakes have been recorded within 50 km since this one.

  1. 2.3 12 km N of Dillon, Montana
  2. 2.0 Western Montana
  3. 1.6 18 km WNW of Pony, Montana
  4. 1.8 3 km NNW of Alder, Montana
  5. 2.5 13 km NNW of Ennis, Montana
  6. 1.9 17 km N of Dillon, Montana
  7. 1.9 12 km NNW of Ennis, Montana
  8. 1.9 8 km ESE of Sheridan, Montana
  9. 1.8 14 km N of Dillon, Montana
  10. 1.7 17 km S of Pony, Montana
  11. 2.2 20 km W of Pony, Montana
  12. 2.3 13 km NNE of Dillon, Montana
  13. 1.5 3 km ESE of Twin Bridges, Montana
  14. 1.6 7 km N of Twin Bridges, Montana
  15. 1.5 8 km S of Harrison, Montana

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

For this area

The largest earthquake within 50 km in our catalogue was M 4.0 on 2016-09-03 — it released about 2,500 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.